Getting elected has never been the point of his ventures into the presidential campaign arena (this is his third, beginning in 1992). Shaking up the system is.

Once again, Nader is out to reform politics and challenge the big-money influence of corporations, wealthy individuals and well-financed interest groups.

At a time when liberalism is out of fashion and the nation seems more prosperous and complacent than ever, Nader-for-president seems a decidedly tough sell. Nader concedes that even liberal members of Congress dismiss the ideas he's pushing, such as universal health care, public financing of elections and guaranteed incomes, as having no chance of becoming law.

"They say, `Don't bother me with pie-in-the-sky stuff,'" Nader says.

He's pursuing what he calls his first "serious campaign" for the presidency. He's accepting contributions, campaigning around the country and delivering a message he hopes will hit home with disaffected liberals, environmentalists, union members and others angered by the Democratic Party's shift to the right during the 1990s.

The Democrats and Republicans are "becoming lookalike parties," he says, "so we have to go third party."

Nader is aiming to do for the Greens what Ross Perot accomplished for his Reform Party: win enough of the vote in November - 5 percent - to earn a share of federal funding this year and in the 2004 election.

On Sunday, Nader is expected to be nominated at the Green Party's national convention in Denver. The other declared candidates are Jello Biafra, former leader of the Dead Kennedys punk rock band, and Stephen Gaskin, founder of The Farm, which once claimed to be the world's largest hippie community.

After single-mindedly pursuing his anti-corporate agenda for more than three decades, Nader, at 66 and graying, appears to have lost none of his intensity or outrage.

He has campaigned in 47 states. With a $5 million budget (a tiny fraction of what Gore and Texas Gov. George W. Bush will spend), his campaign must rely heavily on press coverage. That's why Nader spent a recent afternoon grinding through a long string of interviews at the cluttered townhouse in downtown Washington that serves as his campaign headquarters.

"I want to be president," he says, "for a very simple reason. Because this country needs a very strong progressive movement that challenges the accepted concentration of power and wealth in the hands of global corporations who dominate our government, our workplace, our environment and many other areas of our political economy."

Mordant as ever, he dismisses the Democratic Party as a political weakling that fumbled away control of Congress to the likes of Newt Gingrich in 1994 and failed to take it back in 1996 or 1998.

"If you can't expect the Democratic Party to be able to beat the extreme wing of the opposing party, what else can you expect them to do?" he says. "Imagine what Harry Truman, LBJ or Roosevelt would have done with Newt Gingrich."

Nader says he wouldn't mind if he stole enough votes from Gore to tip the election to Bush. A Democratic loss in November, he suggests, would be "a four-year cold shower" that might shock the party back to its liberal roots.

Polls in states including California, a must-win for Gore, show Nader with nearly 10 percent support. But his strategists there say Nader's prospects could diminish without money for a heavy TV advertising campaign.

He also poses a threat in environmentally conscious Oregon, where his support in the polls is running at 7 percent. In Michigan, one of the battlegrounds that could decide the election, the largest union, the United Auto Workers, has flirted with a Nader endorsement to protest Gore's support for free trade.

According to polls and politicians, Nader's appeal is strongest among voters over the age of 50, environmentalists disillusioned by the belief that Gore has failed to live up to his pro-environment rhetoric, union members bitter over the administration's trade policies and liberals turned off by the Democrats' relentless pursuit of unregulated soft money.

But despite Nader's potential strength in the early going, recent history does not favor candidates who lack the money to run a national advertising campaign.